RF Power Supply Matching for IMD Reflected Wave Suppression
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Solution Overview
Problem
In high-frequency power supply systems for plasma reactors, the fast change in plasma impedance due to low-frequency power supply voltage variations leads to increased inter-modulation distortion, resulting in higher reflected waves that hinder efficient power delivery to the load.
Innovation Solution
A high-frequency power supply system that includes a bias power supply, a source power supply with frequency modulation, and an impedance matching device. The source power supply detects reflected waves and adjusts the modulation start phase and gain to minimize reflections, using a trigger signal synchronized with the bias power supply frequency to optimize matching between the source and load impedances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If impedance variable element of matching device is operated by motor, then matching operation can be performed, but it cannot follow the fast change in plasma impedance due to periodic voltage change of bias power supply
Solution Approach 1:
The patent replaces the motor-operated mechanical impedance adjustment system with an electronic impedance adjustment system. The electronic system can respond to fast changes in plasma impedance caused by periodic bias power supply voltage changes, overcoming the speed limitation of mechanical motors while maintaining impedance matching capability.
Solution Approach 2:
The patent implements dynamic impedance adjustment where the impedance variable element can change its impedance value in real-time according to the periodic changes in plasma impedance. This dynamic response allows the matching device to follow the fast variations caused by the bias power supply frequency without the inertia limitations of mechanical systems.
2Adaptability or versatility
If dual-frequency power supply is provided, then plasma processing can be performed, but inter-modulation distortion increases causing reflected wave to increase
Solution Approach 1:
The patent employs feedback control where the system monitors the reflected wave caused by inter-modulation distortion and adjusts the impedance variable element accordingly. This feedback mechanism minimizes the harmful reflected wave by dynamically compensating for the inter-modulation distortion generated by the dual-frequency power supply operation.
Solution Approach 2:
The patent changes the impedance parameter of the matching device in response to the periodic plasma impedance variations. By adjusting the impedance variable element according to the bias power supply frequency, the system minimizes inter-modulation distortion and reduces reflected wave while maintaining dual-frequency plasma processing capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the process of reducing reflected waves due to inter-modulation distortion, thereby ensuring more efficient and accurate power delivery to the plasma load by dynamically adjusting the modulation parameters based on real-time impedance changes.
Implementation Method 1
a source power supply for supplying a high-frequency output of a second frequency higher than the first frequency, the high-frequency output being frequency modulated with the first frequency
Data Source
AI summary
Proposed are techniques for simplifying the process of suppressing an increase in a reflected wave Pr due to IMD. A high-frequency power supply system for providing high-frequency power to a load includes: a bias power supply for supplying a bias power having a first frequency; a source power supply for supplying a high-frequency output having a second frequency higher than the first frequency and being frequency modulated with the first frequency; and a matching device including an impedance matching circuit for acquiring the bias power and the frequency modulated high-frequency output and achieving impedance matching between the source power supply and the load. The source power supply, in response to a trigger signal for timing having the first frequency, detects a reflected wave while causing a modulation start phase and a modulation amount gain to be varied, and determines an optimum modulation start phase and modulation amount gain that minimize the reflected wave.